We need a little help to get top 4 it looks like.
We dont, the model is wrong. The bookies have us a small favorites to make top 4.
The big mistake the model does is failing to take into account the difficulty of playing strong teams at home. Arsenal have City and United at home. If they had Burnley and Sunderland instead the model would rate them exactly the same. Even Liverpool who have been preety excelent at home with 3 wins and 2 draws are -4 in the model.
The other mild mistake the model does is overating how difficult away games against midtable sides are. Liverpool have West Ham away and Stoke City away where the par is 2. None of us would take that point tally if they offered it to us right now even though the model suggests that is title form. In this case this evens out though because Arsenal has two of those games as well.
In Manchester United case they only have one game away against those teams( away at Saints) while they have a hard home game against Chelsea.
So to recap.
Liverpool has two away games against midtable teams giving us a great chance to make ground in the model.
Arsenal has the same two away games which will also give the chance to make ground but they have two really hard par 3 games so it evens out.
Man United have only one away game that will give them a great chance to make ground while they have only one banana skin game.
EDIT: If you want to make the case that Everton is also a banana skin game it doesnt matter because all 3 of us have Everton at home.
EDIT 2: If I was in charge of the model I would make both home teams 1-6 and away teams 7-12 par 2. In this season the model would be slightly problematic becuase Southampton and Leicester would be overated and Chelsea underated but it would be a failure due to specific circumstances not a structural mistake.
Edit 3: Actually if I was in charge of the model, I would only use the results of the previous season for the first 19 games. After 19 games I would switch to the table at the end of the calendar year and work with that from there on. This small tweak takes care of teams changing their fortunes considerably from one season to another.